People who light up before getting busy report feeling “aphrodisiac effects” in approximately half of cases, while 70% of users say they experienced “enhancement in pleasure and satisfaction,” according to a review of preclinical trials and studies that used human subjects.

Researchers from the University of Catania in Italy and Charles University and Masaryk University in the Czech Republic did not find major discrepancies between men and women in these reports, which means marijuana could be a libido-booster regardless of a person’s sex.

Weed is the most commonly used illicit substance, and for thousands of years, people have documented the plant’s effect on sexual functioning. However, it has attracted little interest from the scientific community, in part because marijuana remains illegal under US federal law and is difficult to research.

We don’t know exactly what role cannabis plays in sex. The mechanisms that make your toes curl are governed by complicated psychological, neurological, and endocrinological systems.

When a user ingests marijuana, chemicals in the plant ride the nervous system to the brain and latch onto molecules called cannabinoid receptors. Those little holding cells influence pleasure, memory, coordination, and cognition, among other functions, which is why getting high affects thinking and behavior. So it’s possible the endocannabinoid system influences sexual behavior.

For the purposes of this study, researchers evaluated several investigations into the effects of cannabis on sexual intercourse that were conducted in the 1970s and ’80s.

In 1970, Erich Goode, a former professor of sociology at Stony Brook University and an author, suggested that frequent, but not heavy marijuana use was associated with aphrodisiac effects in roughly 50% of users surveyed and increased pleasure in about 70% of subjects.

In a 1983 study published in The Journal of Sex Research, researchers interviewed a pool of mostly heterosexual, sexually active people on theperceived effects of marijuana use on sexual behavior. What they found supported Goode’s results. About one-half of users reported an increased desire for a sexual partner they knew, and over two-thirds of subjects said they experienced increased sexual pleasure and satisfaction after using marijuana.

“Many felt marijuana was an aphrodisiac,” the paper’s authors wrote.

In contrast, a 1971 study from Cairo University surveyed several hundred males who had been convicted exclusively for hashish use and detained in Egyptian prisons between 1967 and 1968. Only 23.8% of participants reported ingesting cannabis in order to enhance sexual enjoyment.

There were some catches.

How often users smoked mattered. Smoking about 50 joints over six months showed to be beneficial, while smoking fewer than one joint per week caused a dramatic decrease in sexually enhancing effects, according to Goode’s research for his book, “The Marijuana Smokers.”

Wayne Koff, who today serves as CEO and president of the Human Vaccine Project, found in 1974 that dosage was an important factor. A single joint was sexually stimulating, while higher doses became detrimental to sexual functioning, which suggests “less is more.”

Several other factors could have influenced the results. Psychoactive effects can vary among individuals for a wide variety of reasons, including experience with a substance and expectations for how they’ll feel. The amount of marijuana in a joint varies as well, and the percentage of THC — the main psychoactive ingredient in cannabis — in marijuana is often higher now than it may have been in the 1970s and ’80s.

Consumers shouldn’t expect to find Viagra-branded marijuana behind pharmacy counters anytime soon. The studies investigated in the Pharmacological Research journal are few and decades old. Further research is necessary to understand how cannabis and sex mix.

Should cannabis join ginseng and the maca root vegetable in the razor-thin category of proven aphrodisiacs, it could majorly disrupt the multi-billion dollar erectile dysfunction drug market.

That would be good news for women, who have been largely ignored in the sexual dysfunction arena. A little pink pill known as the “female Viagra” received approval by the Food and Drug Administration in 2015, but it has yet to take hold among consumers.